A child plays at the Restoration Baptist church in Monrovia, Liberia, on Aug. 31. Liberia said it would deny permission for any crew to disembark from ships at the country's four seaports until the Ebola epidemic was under control.(Photo: Dominique Faget, AFP/Getty Images)

The world is allowing the Ebola outbreak to spin out of control, according to a leading humanitarian group helping to treat patients in West Africa.

In a separate speech, the USA's top public health official also called on global leaders to do far more to control the Ebola outbreak that has now spread to five countries.

"I could not possibly overstate the need for an emergency response," said Thomas Frieden, director of the Centers for Disease Control and Prevention, who just returned from visiting Ebola treatment centers in West Africa. "There is a window of opportunity to tamp this down, but that window is closing. ... We need action now."

Separately, the missionary group SIM USA announced Tuesday that another of its workers, an American doctor, has been diagnosed with Ebola in Liberia.

Although health leaders know how to halt the spread of the virus, "the challenge is to scale it up to the massive levels needed to stop Ebola," CDC's Frieden said, noting, "Speed is key. For every day's delay, it becomes harder to stop it."

Frieden said the Ebola outbreak — the largest in the 40-year-history of the virus — is the first true Ebola epidemic, reaching widely into many countries. In the past, Ebola affected much smaller communities.

The World Health Organization reports that more than 3,000 people have been infected with Ebola in five countries of West Africa — Guinea, Sierra Leone, Liberia, Nigeria and Senegal — and more than half have died.

Ebola now threatens the peace and security of the countries affected, Frieden says, noting that 70 staff from the CDC are now working in West Africa.

"This is not just a problem for Africa," Frieden said. "This is a problem for the world, and the world needs to respond."

Failing to control the virus makes it more likely that Ebola will expand to additional countries, and that Ebola could mutate in ways that make it easier to spread, Frieden said. While the risk of such mutations is low, "it's probably not zero."

Doctors Without Borders, one of the leading humanitarian agencies fighting the epidemic in West Africa, said Tuesday that "the world is losing the battle" to contain Ebola.

"Leaders are failing to come to grips with this transnational threat," said Joanne Liu, president of Doctors Without Borders, in a statement. "States have essentially joined a global coalition of inaction."

The group called on countries with the capacity to handle biological disasters — such as pandemics or bioterrorist attacks — to send more boots on the ground, in the form of trained civilian or military medical teams.

"Funding announcements and the deployment of a few experts do not suffice," Liu said. "The clock is ticking and Ebola is winning. The time for meetings and planning is over. It is now time to act. Every day of inaction means more deaths and the slow collapse of societies."

Doctors Without Borders estimates that its hospital in Monrovia, the capital of Liberia, needs another 800 beds. The hospital now has 160 beds.

"Every day, we have to turn sick people away," said Stefan Liljegren, a Doctors Without Borders coordinator in Liberia, in a statement. "I have had to tell ambulance drivers to call me before they arrive with patients, no matter how unwell they are, since we are often unable to admit them."

Frieden, who visited the Ebola wards himself, said wearing multiple layers of "personal protective equipment" — or moon suits — is "roasting hot" in the tropical climates of West Africa. "Sweat pours down into your goggles and eyes," Frieden says. Doctors wearing two sets of gloves have trouble even drawing blood, he said.

"As bad as the situation is now, everything I've seen suggests that it will get worse," Frieden says.

The World Health Organization last week announced that the Ebola outbreak could grow to 20,000 cases and take another six to nine months to contain.

"In some ways, the most upsetting thing I saw was what I didn't see," Frieden said of his trip to West Africa. "I didn't see enough beds for treatment. One facility with 36 beds, that just opened, had 63 patients. Some were laying on the ground. ... I didn't see data coming in from large parts of the country. I didn't see the rapid response that is needed to keep a single cluster from becoming a large outbreak."

A separate Ebola outbreak is occurring in the Democratic Republic of Congo in central Africa. Tests on the viruses in circulation there show that the outbreak is a "distinct and independent event, with no relationship to the outbreak in West Africa," the World Health Organization said Tuesday.

Health workers with the International Federation of the Red Cross and personnel with Doctors Without Borders take participate in a pre-deployment Ebola training exercise on Oct. 29 at Red Cross headquarters in Geneva, Switzerland.
Fabrice Coffrini, AFP/Getty Images

A Kenyan Port Health Services worker tells a boy to return to an observation room for Ebola screening at Jomo Kenyatta International Airport in Nairobi on Oct. 28.
Daniel Irungu, European Pressphoto Agency

A photograph provided by attorney Steven Hyman shows nurse Kaci Hickox in an isolation tent on Oct. 26 at University Hospital in Newark, N.J. Hickox was quarantined in New Jersey after caring for Ebola patients in West Africa. She was being released after being symptom-free for 24 hours and will be flown to Maine. She complained that there was not a shower, flushable toilet, television or reading material in the isolation tent.
Steven Hyman via AP

Amber Vinson, right, a Texas nurse who contracted Ebola after treating an infected patient, hugs members of her nursing team during a press conference after being released from care at Emory University Hospital in Atlanta.
Daniel Shirey, Getty Images

Members of the Community Outreach Team hand out information about Ebola to residents outside an apartment building at 172nd Street and Stratford Avenue in New York. A 5-year-old boy who lives in the building and recently returned to New York City from the West African nation of Guinea is being tested for Ebola after he was rushed to the hospital with symptoms consistent with the disease, according to health officials.
Don Emmert, AFP/Getty Images

New York City Police officers stand in front of 546 West 147th Street, the apartment building of Dr. Craig Spencer on Oct. 25. Spencer, who was working in Africa with the Doctors Without Borders organization, was quarantined after showing symptoms of the virus after his return to New York City.
Bryan Thomas, Getty Images

Members of the Department of Defense's Ebola Military Medical Support Team dress with protective gear during training at San Antonio Military Medical Centerin San Antonio on Oct. 24. The team will consist of 20 critical care nurses, 5 doctors trained in infectious disease, and 5 trainers in infectious disease protocols.
Eric Gay, AP

Members of the media gather in front of the closed Gutter bowling alley, where Craig Spencer bowled recently in Brooklyn, N.Y. Spencer, who tested positive as New York's first case of Ebola, is in isolation at Bellevue Hospital.
Jewel Samad, AFP/Getty Images

Health alerts regarding people who may have traveled to particular West African countries are posted in the lobby of Bellevue Hospital in New York. Craig Spencer, a resident of New York City and a member of Doctors Without Borders, was admitted to Bellevue Thursday and has been diagnosed with Ebola.
Mark Lennihan, AP

Women work on a protective suit for use in handling people infected with the Ebola virus in a sewing room at Lakeland Industries Inc. Lakeland, a global manufacturer of industrial protective clothing, produces suits to be worm by healthcare workers and others being exposed to Ebola.
Johannes Eisele, AFP/Getty Images

Spec. Jason Dumas, left, helps Spec. David Quichocho, right, with his protective boots during a training session at Ft. Carson. Both soldiers are from the 615th Engineer Company, 52nd Engineer Battalion which will be deploying approximately 160 engineers to West Africa to help with the fight against Ebola.
Jerilee Bennett, The Colorado Springs Gazette via AP

A Liberian health worker disinfects a street corner where a suspected Ebola patient was picked up and taken into an ambulance to be transported to an Ebola treatment unit in Monrovia, Liberia.
Ahmed Jallanzo, European PressPhoto Agency

Health workers from the Liberian Red Cross wear protective gear as they shovel sand which will be used to absorb fluids emitted from the bodies of Ebola victims in front of the ELWA 2 Ebola management center in Monrovia.
Zoom Dosso, AFP/Getty Images

German volunteering soldiers wear protective equipment in Appen, Germany, as they take part in an intensive course to prepare volunteer helpers for their deployment in Ebola-hit countries.
Bodo Marks, AFP/Getty Images

Doctors and nurses take part in training in treating infectious diseases in an isolation room during a presentation on diagnosing and treating patients with Ebola virus symptoms in Bern, Switzerland, on Oct. 23.
Alessandro Della Valle, European Pressphoto Agency

Filipino health workers hold anti-government placards outside a public hospital intended for Ebola patients in Manila. The group criticized the government in its hope of combating and responding to the threat of Ebola, if it hits the country. Placard reads; "The government can't provide sufficient funding for Tuberculosis let alone Ebola."
Dennis M. Sabangan, european pressphoto agency

The Taiwanese Centers for Disease Control displays protective gear during a demonstration on how to handle Ebola patients in Taipei, Taiwan. Taiwan has not reported any Ebola infection cases but has designated six hospitals to treat Ebola patients.
Taiwan CDC via European Pressphoto Agency

Ashoka Mukpo shakes hands with physician Kristina Bailey after being released from the treatment unit at the Nebraska Medical Center on Oct. 22 in Omaha. Mukpo was treated and released at UNMC after contracting Ebola in West Africa while working as a freelance journalist.
Taylor Wilson, Nebraska Medicine via Getty Images

A health care worker in protective gear sprays disinfectant around the house of a person suspected to have Ebola virus in Port Loko Community, on the outskirts of Freetown, Sierra Leone.
Michael Duff, AP

British Army medics board an airplane as they depart for Sierra Leone at RAF Brize Norton in Brize Norton, England. They will man the Ebola Training Academy, instructing the health care workers who will be working in the five Ebola Treatment Units the UK is currently building.
Matt Cardy, Getty Images

Participants in an Ebola education session look over printed materials in New York. Thousands of participants, mostly health care workers, attended the session to review basic facts about Ebola and updated guidelines for protection against its spread.
Seth Wenig, AP

Barbara Smith, left, a nurse at Mount Sinai Health Systems, and Dr. Bryan Christiansen, a member of the Center for Disease Control and Prevention's Infection Control Team for the Ebola Response, demonstrate proper safety techniques during an Ebola education session for healthcare workers at the Jacobs Javits Center on Oct. 21 in New York.
Timothy A. Clary, AFP/Getty Images

British military medics wait at a departure lounge before boarding an aircraft for Sierra Leone at Royal Air Force base Brize Norton in England. The medics from 35 Squadron, 5th Medical Regiment, will staff the Ebola Training Academy, instructing health care workers who will be working at five treatment units.
Matt Cardy, Getty Images

Passengers leave the Carnival Magic after docking in Galveston. A Dallas lab supervisor who handled a specimen from Thomas Eric Duncan, who died last week after contracting Ebola, was in voluntary isolation in her cabin aboard the cruise ship. She tested negative.
Jennifer Reynolds, AP

Men in hazmat suits clean the station where a person became sick at a DART train station in Dallas on Oct. 18. The person had supposedly been at the same apartment complex where Ebola patient Thomas Eric Duncan was staying.
Larry W. Smith, European Pressphoto Agency

A health worker takes a baby from his mother as he prepares to carry the infant to a reopened Ebola holding center on Oct. 17 in the West Point neighborhood in Monrovia, Liberia. The baby, his mother and grandmother were all taken to the Ebola center after they tested positive for a fever.
John Moore, Getty Images

An Ebola tracing coordinator checks the temperature of Jessica Sompon and discovers she has a fever in the West Point neighborhood in Monrovia. A family member living in the home died the previous day from Ebola.
John Moore, Getty Images

A custodial worker leaves after cleaning Davis Elementary School in Dallas, Texas. The school was closed after it was discovered that a health care worker who treated one of the Texas Health Presbyterian Hospital nurses infected with the Ebola virus lives at a home with students from the school.
Chip Somodevilla, Getty Images

Employees with Cleaning Guys Environmental carry disinfecting equipment into North Belton Middle School. The Central Texas school district has temporarily closed three of its campuses after a family of four, including two students from the district, traveled on the same flight as a nurse who has since been diagnosed with Ebola.
Rusty Schramm, The Temple Daily Telegram, via AP

An ambulance carrying Texas Health Presbyterian Hospital nurse Nina Pham leaves the Frederick Municipal Airport on Oct. 16 in Frederick, Md. Pham contracted Ebola when she was part of a team who cared for Thomas Eric Duncan, a Liberian man who eventually died from the virus on Oct. 8.
Mark Wilson, Getty Images

People for a convoy transporting Texas nurse Nina Pham after she arrived at Frederick Municipal Airport on Oct. 16 in Frederick, Md. Pham was moved to the National Institutes of Health facility in Bethesda, Md.
Patrick Semansky, AP

Hospital staffers cheer as an ambulance transporting nurse Nina Pham, who is infected with Ebola, leaves Texas Health Presbyterian Hospital for Love Field in Dallas. Dozens of co-workers gathered outside the hospital and waved signs in support as Pham was flown to a health care facility in Maryland for treatment.
G.J. McCarthy, The Dallas Morning News, via AP

After putting on their protective gear, hazmat workers on Oct. 16 prepare to enter the apartment at The Village Bend East complex where a second health care worker who has tested positive for the Ebola virus resides, in Dallas. Nurse Amber Vinson joins Nina Pham as health workers who have contracted the Ebola virus at Texas Heath Presbyterian Hospital while treating patient Thomas Eric Duncan, who has since died.
Mike Stone, Getty Images

Hazmat workers with Protect Environmental unload barrels in preparation for decontaminating an apartment at The Village Bend East apartment complex where Amber Vinson, a second health care worker who has tested positive for the Ebola virus, resides in Dallas.
Mike Stone, Getty Images

Members of the Dallas Fire-Rescue Haz Mat Unit tapes off the door of a second health care worker who tested positive for the Ebola virus on Oct. 15 at the The Village Bend East apartments in Dallas. The worker at Texas Health Presbyterian Hospital was monitoring herself for symptoms and reported a fever. She was in isolation within 90 minutes.
Sana Syed, City of Dallas, via AP

Heinz Schuhmacher, left, and Marc Dangel, advisers for infection prevention, show how to properly put on protective garments during a demonstration on how to handle Ebola cases at the university hospital in Basel, Switzerland. The World Health Organization projects the Ebola infection rates in West Africa will rise to 5,000 to10,000 new cases a week by December.
Ennio Leanza, European Pressphoto Agency

Aid workers from the Liberian Medical Renaissance League stage an Ebola awareness event in Monrovia, Liberia. The group performs street dramas to educate the public on Ebola symptoms and the handling of people who are infected with the virus.
John Moore, Getty Images

U.S. Army Staff Sgt. Samuel Hines, left, helps U.S. Army Cpl. Zachary Wicker tape gloves to his uniform during a demonstration at Fort Bliss, Texas. Five hundred soldiers from Fort Bliss are preparing for deployment to West Africa to provide support in a military effort to contain the Ebola outbreak.
Juan Carlos LLorca, AP

Bentley, the one year-old King Charles Spaniel belonging to nurse Nina Pham who contracted Ebola, is removed from her apartment to be cared for at an undisclosed location.
Sana Syed, City of Dallas, via AP

A Liberian health worker from a Red Cross burial team is disinfected after collecting the bodies of Ebola victims in the Point Four community outside Monrovia.
Ahmed Jallanzo, European Pressphoto Agency

Ebola survivor Abrahim Quota, 5, is handed a letter confirming his recovery from the virus after he and other survivors were released from the JFK Ebola treatment center in Monrovia, Liberia. Both of his parents died at the center, and Health Ministry workers planned to take him to live with his closest relatives.
John Moore, Getty Images

Health workers dress in protective clothing before taking the body of an Ebola victim from the Island Clinic Ebola treatment center in Monrovia, Liberia. A planned strike at Ebola treatment centers was averted as most nurses and health care workers reported for work. Health workers have asked for increased hazard pay. They are one of the most high-risk groups for Ebola infection. Nearly 100 of them have died in Liberia.
John Moore, Getty Images

Mohammed Jan Jallo, 40, smiles while looking over a letter from Doctors Without Borders (MSF), labeling him as Ebola-free, following his recovery at the MSF treatment center in Paynesville, Liberia. He said he works as a vendor in a market and has no idea from whom he contracted the disease.
John Moore, Getty Images

Maria Uruchimadecriollo cleans a bathroom at JFK Terminal 4 international arrivals in Jamaica, N.Y., on Oct. 11. Uruchimadecriollo is wearing a mask that her husband bought for her yesterday in hopes of keeping her safe from the Ebola virus.
Jennifer S. Altman, for USA TODAY

A burial team disinfects the body of Ebola victim Mekie Nagbe before removing it for cremation on Oct. 10 in Monrovia, Liberia. Nagbe, a market vendor, collapsed and died outside her home earlier in the morning as she was about to walk to a treatment center.
John Moore, Getty Images

Medical practitioners shout against Spain's Prime Minister Mariano Rajoy during his visit to the Carlos III hospital in Madrid, Spain, Friday, Oct. 10, 2014. A Spanish hospital official says the nursing assistant infected with Ebola is "stable," hours after authorities described her condition as critical. She is the first person known to have caught the disease outside the outbreak zone in West Africa. She contracted the virus while helping treat a Spanish missionary who became infected in West Africa, and later died. (AP Photo/Daniel Ochoa de Olza) ORG XMIT: DO113
Daniel Ochoa de Olza, AP

An ambulance is readied by technicians wearing biological hazard clothing as they prepare to transport a Guinean patient suspected of having contracted Ebola, in Cascavel, Brazil.
Luiz Carlos Cruz, AFP/Getty Images

A passenger is checked at checkpoint at John F. Kennedy International Airport on Oct. 9 in Queens, New York. Travelers arriving from Ebola-stricken countries in West Africa will have their temperature taken and fill out a questionnaire when they arrive at one of five major U.S. airports.
Justin Lane, European Pressphoto Agency

A health worker takes the temperature of U.S. Marines arriving to help stem the Ebola outbreak during Operation United Assistance near Monrovia, Liberia. Ninety Marines will support the American effort to contain the epidemic.
John Moore, Getty Images

U.S. Air Force personnel put up tents to house a 25-bed U.S.-built hospital for sick Liberian health workers as part of Operation United Assistance in Monrovia, Liberia. President Obama has committed up to 4,000 troops in West Africa to combat the Ebola epidemic.
John Moore, Getty Images

U.S. Marines arrive as part of Operation United Assistance in Monrovia, Liberia. Around 90 Marines, the largest group of U.S. military yet, arrived on MV-22 Ospreys and KC-130 transport planes to support the American effort to contain the Ebola epidemic.
John Moore, Getty Images

Moroccan health workers screen passengers at the arrivals hall of the Mohammed V airport in Casablanca. Air Maroc, along with Air France and Brussels Airlines, are still flying to Ebola-hit West Africa, with the backing of the World Health Organization. The WHO has urged the airlines to keep flying, saying the risk to public health from air travel itself is low and that flights bring needed aid workers and supplies.
Abdeljalil Bounhar, AP

U.S. Air Force airmen from the 633rd Medical Group set up tents for a 25-bed hospital to aid Liberian health workers infected with Ebola near Monrovia, Liberia. The airmen are setting up the modular hospital, known by the military as an expeditionary medical support system (EMEDS), near the international airport outside of Monrovia. The airmen will train U.S. public health service members in using the hospital's medical equipment, but will not be involved in treatment of Ebola patients.
John Moore, Getty Images

Licensed clinician Margaret Chilcott removes her outer gloves before disrobing and sanitizing in Anniston, Ala. The Centers for Disease Control and Prevention (CDC) has developed an introductory training course for licensed clinicians. According to the CDC, the course is to ensure that clinicians intending to provide medical care to patients with Ebola have sufficient knowledge of the disease.
Brynn Anderson, AP